Why 12-speed?

The big news is, of course, the move from 11 to 12-speed.

The addition of another cog allows for smaller jumps between gears in the middle of the cassette. This is not only useful in a double-chainring drivetrain, but it also opens up options for 1x drivetrains (more on those in a moment).

The new cassette also adopts a 10t small cog.

The pictured bike is set up with a 50-37t chainring combo and a 10-28 cassette. A gear of 50x10 is similar to that of 53x11 — the top gear ratio commonly used by professional riders — at a marginally lower weight.

Mounted to a wheel, it’s hard to be certain how the cassette is constructed, but it appears the first 11 cogs borrow the one-piece Hollowdome construction — which sees a single forged steel billet milled into a one-piece cassette — used on the original eTap cassette. The largest cog, which is made from a different material to the rest of the cassette, then appears to be mounted separately.

We think it’s safe to assume that the new 12-speed cassette will be mounted via SRAM’s XDR (XD Road) driver.

The XDR freehub body is based on SRAM’s XD driver — which was introduced with the first generation Eagle drivetrain — but is 1.85mm wider.

This extra width is required because unlike on an Eagle cassette where the large 50t cog can be dished over the spokes, a road-sized cassette is not large enough to accommodate this.

The main body of the rear derailleur is constructed with an alloy main body paired with a composite cage, which is slightly chunkier than the outgoing model.

The removable battery looks identical to the one used on the outgoing generation, suggesting these will likely be cross-compatible.

What chain does SRAM eTap 12-speed use?

We didn't have a chance to whip out our calipers to measure the width of the new chain, but we think it’s likely that the new eTap 12-speed chain will be narrower than an 11-speed chain.

Looking closely, the inner plates of the chain are also considerably chunkier than on an 11-speed chain, with no cut outs or shaping to the upper face of the plate.

Assuming the chain is narrower, we imagine this extra material is required to maintain strength and deal with more extreme cross-chaining angles caused by the wider cassette.

One-piece chainrings for new SRAM eTap 12-speed

It’s not entirely clear from the photo, but the chainrings are a one-piece spiderless construction. This is similar to the setup used on, among others, Cannondale’s Hollowgram cranks.

The bike pictured is set up with a 50-37 chainring combo, but we’ve also seen a 50-36t combo at the Saitama Criterium, suggesting a number of options will likely be available.

The chainrings are mounted to a set of carbon arms that, visually at least, appear similar to existing cranks from the brand. This is fitted with a Quarq power meter.

Will there be a 1x 12-speed SRAM eTap groupset?

So far, we have only seen the groupset in a double guise, but it’s likely that a 1x version will also be available.

Whether 1x groupsets will be adopted by the notoriously conservative pro-peloton is a another question; its relationship with single-ring drivetrains has so far been — to be generous — fairly rocky. However, should a 1x option become available, it’s sure to be popular in the world of gravel and ‘cross.

Will SRAM 12-speed eTap be disc only?

At present, we have only seen a disc brake version of the groupset. While there’s still wide demand for rim brakes in both the professional and enthusiast world, we still wouldn’t be surprised if only a disc version will be available, but that is pure speculation.

That’s all we have so far. We’re here for the duration of the Tour Down Under, so we will try to get more photos and details as the race proceeds. In the meantime, let us know if you have any questions and be sure to leave your thoughts below.

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